Mass spectrometers are used for determining the chemical composition of a sample, including the masses and chemical structures of sample molecules. Mass spectrometers are precision instruments and measure the constituent chemicals in a sample by measuring the analog signal from, for example, a detector after ions are sorted according to their mass by, for example, an ion trap analyzer. There is a need to produce a spectrum describing the relationship between the mass/charge of ions and their relative abundance, calculated from signals measured from the mass analyzer such as voltage, time, or current. Also, the mass assignment or calibration may change. These changes may be short term and temporary, for example, by changing the ambient temperature; or they may be long term and/or permanent, for example as the instrument ages. One way mass spectrometers may be tuned and calibrated is by using a calibration algorithm, typically performed at the startup of the mass spectrometer or as needed, which may be as often as several times per day to as infrequent as annual.
Previous systems for calibrating a mass spectrometer typically include using either a sample manually applied to the inlet of the instrument or using a vial of liquid sample that is contained within the instrument and has a volatility sufficiently high to generate a concentration in the headspace sufficient to be measured by the mass spectrometer to perform the calibration. A common calibrant is perfluorotributylamine (PFTBA) but many others exist. When the instrument is being calibrated, a valve may open, allowing gas from the vial to flow into the vacuum chamber of the instrument. However, in the case of a portable mass spectrometer, movement may cause the sample to be agitated and potentially contaminate the system. Additionally, the concentration of sample is dependent upon physical parameters, such as volatility, amount of calibrant remaining, temperature, etc.; therefore, it can be difficult to deliver a consistent amount of calibrant to the mass spectrometer, which not only presents difficulty in calibration but can also contaminate the system. Some particularly sticky liquid samples might even last longer, preventing accurate readings from the mass spectrometer for days or even weeks.
Thus, there exists a need to provide a calibrant container for a portable mass spectrometer that eliminates issues associated with movement and can provide a more consistent, regulated sample to the instrument for calibration.